How did the Rebels flee Hoth with the Empire on their heels?

"The Rebels are alerted to our presence..."

Because of bad planning by the Empire the Rebels had enough time to perform their escape plan and to put up their shields before the Empire could get their forces into place to stop them.

 

Or Luke on Crait!

Just doing a little research on this one, but from what I can see it boils down to a few other things, including what's already been mentioned here.

1) In family guy, someone makes a joke that they can literally fly in infinite directions away from the planet, so why fly directly toward the ISD fleet? In actuality in the movie, the fleet actually is spread out across the planet to prevent this very thing from happening. This also means that the Ion canon can sometimes fire on a nearby Star Destroyer, and with them already spread thin, this made escape for a lot of GR-75s a possibility.

2) Even so, some estimates show a causality rate of as high as 50% for the Rebels. They definitely didn't all get away.

 

Riddled with plot holes and logical fallacy!!!!L337

 

Childhood ruuuuuuuuuuuuuuuuuinnnnnnnnnnnned!!!!!!!!!!!!!

 

I would assume not every transport and ship made it off of Hoth and we only see the first transport actually make it past a Star Destroyer. We know that the alliance was scattered after having to flee Hoth so it could be possible that the Empire was just focused on trying to capture as many as possible while also focusing on the ground assault. It is also possible that the commanders of the Star Destroyers were not certain that the ion cannon was no longer a threat immediately after Vader invaded the base so that could have played another role in why so many ships were able to escape.

 

It is just another example of dont think about the tactics so much. When I see people complain about FO tactics in TLJ I roll my eyes because every single movie has poor tactical military choices. Movies dont call attention to tactics much so the audience should follow that.

 

I don't even think that the Reber force on Hoth were the main one. As the comics tell us, they already had the Mon Calamari ships by ESB, so no matter how many ships escaped Hoth, the RA had plenty to rely on. How did they end up on Hoth in the first place is yet to be see, though.

 

I thought a large amount of the high command for the rebel alliance was on Hoth and that is why they were so focused on evacuating everybody?

 

Were they? When the movie came out it was probably supposed to be this way. But I haven't seen ESB in a while and the current canon hasn't reached Hoth yet. The SW comics currently stopped after they aquaired the Mon Cala ships. We know Mon Mothma was part of the Rebellion already and she wasn't on Hoth.

 

I haven't read it yet, but I believe Battlefront Twilight Company touches a little bit on this or at least mentions some of the leadership currently on Hoth during the time of the evacuation.

 

Yep.
What @HuskyRunner said.
In BF Twilight Co. just 'fore the Hoth Battle, RA high command were there then left.
Can't 'member the name of that Destroyer that got took out by the Ion cannon but 'coz it was out, that hole in the blockade let a bunch more Rebels ships through before the Empire could readjust.

 

Aahh, I won't to able to get to that in a while...

Still, a new comic came out (SW 50) and, not to spoil anything important, the idea for the Rebel fleet at the time was to scatter, go into hiding and gather up when the need comes. Like a hidden blade.

 

According to a deleted scene from the film (illustrated below) one snowtrooper did inform Vader upon his arrival that 17 Alliance ships had been destroyed (though it's not clear whether that referred to transports and escort fighters).



As a matter of fact, I'd believe that the Alliance shortly opened the shields and sent the transport ships and fighters straight into the direction of Star Destroyers so that the ion cannon had something to aim for. I guess after the first disabled "Catch of the day" Star Destroyer Piett got more cautious and they tried to shoot down the escaping Alliance ships from a rather safe (but less effective) distance.

I'm rather confident that Vader's strategy relied on General Veers to take out ASAP the shield power generators and right next the ion cannon.

 

As noted I think Vader would prefer to use bombing runs then let air power or destroyers remove any remaining threats. Star Wars canon has a term for it, I can never recall: Bravo Zulu Delta or something. That can level most planets or wipe out the surface of a world. Imperial commanders avoided this tactic if possible because it leaves little left & does a lot of havoc.

 

It’s because Admiral Ozzel was a bozo.